Hammer drill



Sept. 9, 1958 v E. A. MORI 2,851,010

HAMMER DRILL Filed May 16, 1957 2 sheets-sheet 1 nv m Sept. 9, 1958 E. A. MQRl 2,851,010

HAMMER DRILL Filed May 16, 1957 2 SheeS--Shee 2 IN VENTOR. ERA/57 4. A/O/Q/ United 2,851,010 HAMMER DRILL ErnestA. Mori, Pittsburgh, Pa., assigner to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Application May 16, 1957, Serial No. 659,709

7 Claims. (chui- 25) `howcver, has certain shortcomings which have been largelyy eliminated in the present invention.

This invention provides a rotary percussion drill having long trouble-free service life, improved hammer efciency, and high percussive frequency. These advantages result from a construction which has improved positive valve action, which provides a hydraulic fcushion for the valve andv the hammer at the top of their respective strokes, and which provides for the hammer to strike directly on the anvil without any intervening mechanical parts which may break or become battered. In the drill of this invention a higher hammer frequency is attained together with more eicient hammer operation and these result in attainment of higher rates of penetration during drilling.

rates Patent The drill mechanism show-n in Topanelian Patent 2,661,928 employs two hammers the lower of which strikes directly on the anvil and the upper. of which strikes on top of the lower hammer. While this mechanism provides two hammer blows per cycle of operation itA has been found that the energy delivered to the drill bit by the upper hammer is low because of the intervening member and accordingly the desired etiicacy of the double blow per cycle is Inot realized. It has been found more effective to employ a single hammer rimpacting directly onv the bit stem and to increase the operating frequency of thisl hammer. Such a result is accomplished by the present invention.

Another defectV in the prior devices was occasional faulty valve action which resulted in short and inelective hammer strokes. This has been corrected in thepresent invention by providing hydraulic valve-clamping areas so that the valve seal is tightly maintained by the hydraulic operating pressure, and released at the proper moment in the operating cycle by hydraulic action ,ini-1 tiatvedv by other cooperating members of the mechanism.

The advantages of the drill of this inventiony are yat#` tained by employing a valve above the hammer and by providing the lower end of the valve with an enlargement or head which cooperates with a va'lv'e-c'ylinderVv structure so as to quickly release and open the valve; The structureis further improved by reducing the sealing' surface of the valve'so that a high sealing force per unit area is attainedand this provides a positiveseal against the top of the hammer thereby insuring consistent hammer operation and eliminating short strokes due to faulty valve seal. Further, by providing a hydraulic cushion for the hammer at the top of its stroke the time required to `reverse the upward motion` of the hammer is materially i may be relieved slightly as at 16. The inside diameter of fice 2 "shortened thereby reducing the operating time cycle. In addition, the valve is provided with ahydraulic cushion at its most open position so as to quickly return it t'ol the closed orstarting position, thereby further Areducing the time cycle. The resulting hammer frequen- Cyiis thus increased very materially.V Y This" invention is illustrated in the accompanying drawings forming a part of this specification, and in which Figure l is a longitudinal section taken through the upper portion of a preferred embodiment of the drill; Figure 2 is a longitudinal section'taken through the intermediate portion of the drillV of Figure l; Figure 3 is a longitudinal section taken throughthe lowery portion of the drill of Figures 1 and 2; and l Figures 4 tov l0 are diagrammatic representations lustrating successive phases' in the cyclic operation of the drill'.

Reference is made to the drawings in which like numerals indicate the same element in the various views and diagrams. l

In' Figure l,A adapter 1 serves to connect therdrill aS- sembly: with theV drill stem (not shown) by means of conventional drill collar threads. The drill stem has a central passage as is conventional for supplying drilling fluid to the drill bit and adapter 1 is also provided with a' central passage 2 for the purpose of admitting the pressurized drilling lluidy into the drill mechanism.A A cylindrical upper housing 3 is screwed into adapter luby means of threads 4 and a portion 5 of the adapter of reduced' diameter extends' into the upper4 housing 3 with an annular clearancev 6` between them. The annular clearance6 is sufficiently large `to permit free flow of, drilling uid between thepo'rtion 5 and the inside vof upper housing' 3i and to this end the area of annular clearance o shouldV be substantially the same as thatof passage 2'. Diagonally drilled openings 7 permit drilling huid to pass fromv the passage 2 into the annular clearance 6; The lower end of the extension 5 of adapter 1 is-borel out as shown to form an-inverted? cup-like cylinder 5 5 which accommodatesa valve assembly to be more fully described later. y The lower end of the upper housing 3 is threaded and screwed to a member 8 by means of threads 9 shown in the upper' part of Figure 2. The member S isjsubstan tially of the same outside diameter as housing 3, but has a much smaller internal diameter. Member Srhas screwed toits lower end a cylindrical lower housing 10 by means .of threads-11. Member 8 thus forms a constrictionrin-` termediate the upper housing 3 and the lower housing 10. The lower en'd of housing 10 is fastened to a bit-stem guidel 13 bymeans of threads 14 as shown in'Fig'ure 3`. vThe bitstem guide 13 has a hexagonal central openingl which lower housing 10 has adownward facingV shoulder vat 12 (Figure 2). kAn extension 17 at the upper end of the bit stem guide 13 provides for clamping between itand the shoulder 12 theelernents 18, 19, and 20. AMember 18 is agsplit retaining ring made in two semi-circular sections'.v Member 19 is an annular cylindrical cage having rings 21 and 22 at itslower and upper extremities respectively, and;

having openings in the form of slots- 23 cut lin the Vwall betweenithe rings'. The member 20 is an annular spacer ringwhih'has been spirally cut as at 24 in order to provide axial resilience to the spacer ring. By making the extension 17 `ot' the bit stem of appropriate length, the parts 18 arid 19 are rmly held in place by axial compression ofthe member 20.

siidabiy disposed in' the bit-Stem guide 13 is a bifsteni" 25 that is substantially circular at its lower eiidv and isy threaded as at to receive a conventional drill bit; inV customary manner. The bit stern 25 is provided with'av central passage 27 tofp'rovidedrilling uid access'tothe" bit. Immediately above the lower portion of the bit stem is a hexagonal portion which forms a sliding fit on the hexagonal internal bore 1S of bit-stem guide 13. The purpose of the hexagonal connection between bit-stem guide 13 and bit stern 25 is to transmit drilling torque to the bit stem and bit when the drill pipe and drill assembly are rotated in conventional manner. It is apparent that while a hexagonal connection between members 13 and 25 is shown in the drawing, other axially-slidable means for providing transmission of torque from the bit-stem guide 13 to the bit stern 25 may be provided, such as a square connection, splines, keyways, etc. The bit stem 25 is reduced in diameter as at 28 above the hexagonal portion 15 and forms a sliding t in the upper part of bit-stem guide 13. The upper end of the bit stem is still further reduced in diameter in the region 29 and enlarged slightly again at 30 to a diameter no larger than its diameter at 28. The retaining ring 1S makes a sliding t around the reduced diameter 29, and the shoulder 31 thus prevents the bit stern from dropping out of the assembly after it is made up.

It is apparent that when the drill mechanism is suspended, the bit stem 25 will drop and will be supported by the shoulder 31 resting on the upper surface of retaining ring 18. When the drill is set on the bottom of the hole, the bit stem 25 may slide upward in the bit-stem guide 13 to occupy the position shown in Figure 3. Fluid in the annular space between the bit stem and the bit-stem guide may escape through the clearance in the sliding t and the cuts in the split retaining ring 18. Dimensions of the various parts 13, 18, and 25 are so arranged that when the drill is set on bottom, weight is transferred from the bottom of the bit-stem guide 13 to the shoulder 32 of the bit stem 25 whereby weight is applied to the drill bit.

Inside the housing and above the bit stem there is disposed a hammer 33, the lower end of whose body portion is shown at the top of Figure 3. The body of hammer 33 is generally annular in shape and has a central passageway 34 which is in register with the passage 27 of the bit stem. The hammer 33 is enlarged slightly in diameter at 35 and this portion of the hammer body slides freely on the lands of the inside surface of cage 19. The open slots 23 in the cage permit fluid to by-pass the region of enlarged diameter 35, the lands of the cage yat the same time contacting the hammer portion 35 thereby guiding the hammer in the mechanism. The body of hammer 33 is of considerable length as shown in Figure 2 and has at its upper end a neck 36 which forms a sliding t on the inside of member 8. A compression spring 37 is disposed between the bottom of member 8 and a shoulder 38 on hammer 33. The upper end of the neck 36 is threaded at 39 and has screwed thereto a head 40 which also has a central opening 41 in register with the opening 57 in the neck 36. The head after being tightly screwed on the top of hammer 33 may be locked in place by means of a pin or weld (not shown).

The longitudinal dimensions of the hammer assembly are such that it will have considerable vertical movement when the drill mechanism is resting on bottom as shown in Figure 3. In its lowermost position the hammer 33 rests on the top of bit stem 25. The upper limit of its travel occurs when the shoulder 42 of the hammer is substantially opposite the lower edge 43 of the ring 22 of cage 19. At this point in the upward travel of the hammer, iluid becomes trapped in the annular space around the hammer below the member 8 and above the lower edge 43 of ring 22, and this forms a hydraulic cushion at the upper extremity of hammer motion.

Above the hammer there is disposed a valve mechanism as shown in Figure 1, comprising valve body 44 having a longitudinal passage 45 which is in register with the longitudinal passage of the hammer assembly. The passage 45 is countersunk at 46 so that when the valve ele ment 44 rests on top of the hammer there is a relatively small annular area of contact at 47. The body of valve 44 has a diameter that is larger than the diameter of the hammer neck 36, and the countersink 46 intersects the bottom surface of the valve at a diameter that is not smaller than the diameter of the body of valve 44. The valve body 44 has an outside diameter that forms a sliding fit in a wear ring 49 which is pressed into a counterbore at the lower end of cylinder 55. The internal diameter of the wear ring is smaller than the internal diameter of the cylinder, so that after the wear ring is pressed into the cylinder, the upper part of the wear ring forms an internal projection into the cylinder. The valve 44 has a head 48 at its lower end and the wear ring 49 is counterbored at 50 to an internal diameter that is a sliding lit on the head 48 of valve 44. The valve element 44 will in its lowermost position rest on top of the hammer at 47 and .in its upward travel the shoulder 51 enters the lower end of the counterbore 50. The outer cylindrical surface of the valve 44 has a plurality of grooves 52 cut therein, but the grooves 52 do not reach the shoulder 51. The grooves 52 form by-pass channels whose purpose is to permit drilling fluid trapped above the shoulder 51 in the region 50 access to the cylinder space above the wear ring 49, so that thc head 48 of the valve can enter the counterbore 50. Near the upper end of the valve 44 there are provided a number of openings 53 from the outer surface of the valve to its central channel 45. The upper end of the valve 44 has a shoulder 54 which accommodates a compression spring 56 disposed between the shoulder 54 and the closed end of the cylinder 55.

The longitudinal dimensions of the valve assembly 44 and the wear ring 49 are such that when the drill is suspended off bottom and the shoulder 31 (Figure 3) of the bit stem rests against the top of the ring 18, and the hammer rests on top of the bit stem, and the valve 44 rests on top of the hammer, the passageways 53 are just below the bottom of the internal projection of wear ring 49. In this position drilling luid enters through the passage 2, holes 7, annular space 6, counterbore 50. holes 53, passage 45, passage 57, passage 34, passage 27 and thence to the drill bit, so that circulation of drilling uid may be established while runuing the drill into the hole without operating the drill mechanism. When the drill is set on bottom and brought into the position shown 1n Figures l, 2 and 3, the holes 53 are no longer in communication with the annular space 6, whereupon the drill mechanism is caused to operate as will be described later. The grooves 52 are so arranged that their upper end passes the upper end of wear ring 49 as the shoulder 51 enters the counterbore 50. Due to the bypassing eect of the grooves 52, the head 43 of the valve may enter the counterbore 50 until the bottom of the grooves 52 reaches the top of the counterbore 50, after which iluid trapped in the counterbore acts as a hydraulic cushion and terminates upward motion of the valve 44. The longitudinal spacing of the hammer and valve assemblies 1s such that the hammer reaches its upper hydraulic cushion stop (when shoulder 42 reaches the lower edge 43 of ring 22) just after the valve-head shoulder 51 has entered the counterbore 50.

Operation of the mechanism will be more clearly understood by reference to the diagrams of Figures 4-l0 showing diagrammatically the various phases during the operating cycle of the drill mechanism. In the diagrams the numerals indicate the same elements as in Figures 1-3 described above. Figure 4 shows the drill mechanism in the olf-bottom or rotatng-in position. The bit stem 25 is in its lowermost position and the by-pass holes 53 allow drilling iluid to pass from the annular space 6 to the central passages of the various parts thence to the drill bit at the lower end of the bit stern as previously described. Figure 5 shows the arrangement (also shown in Figures l-B) when the drill is on bottom and about to begin a cycle of hammer operabetween the valve body 44 and the neck 36.

tion. The` holes 53 have now been cut olf and the Dressur-izedI drillingy fluid will raise the hammer and valve. I-nasmuch as drilling fluid is now trapped and cannot pass between the valve and the hammer, the resultingy pressure build-up raises the hammer and valve as shown in Figure 6.j The lifting force is the effective pressure differential times the difference in cross-sectional area v This force ac ts on the bottom annular shoulder of the head 40Y and lifts the hammer and valve against the force of gravity and compression ofthe respective springs. Atthe same time there is a clamping force holding the valve head 4S against the top of the hammer (at the surface 47 in Figure 2) equal to the elective pressure differential timesthe difference in cross-sectional area between the valve body 44 and the outsideV diameter of the top of hammer head 40. As this clamping force is applied over ay-Yrestricted area 47 it will etfect'a good seal at all times. Figure 7 shows the valve head 48 entering the counterbore 50 of the cylinderl 55, l theA cylinder S an additional upward force acts on the valve-44, namely on lower surfaceV of the valve head thatis beyond (outside) the outside diameter of part 4G.- This additional upward force tends to accelerate the valve upward and as a` consequence the seal at 47 is quickly broken. Figure 8 shows thehammer in its uppermost position but the valve has continued to move upward to break the seal. As soon as the hammer reaches its uppermost position as shown in Figure 8, which occurs when shoulderk 42 "(Figure 2)y is opposite the edge 43 of -ring 22, upward motion of the hammer is arrested. kAt this pointy the hydraulic cushion reverses the upward motion ofthe hammer and it begins to fall until it strikes a percussive blow on the bit stem as shown iii-Figurey 9. Thevalve, of course, immediately also falls, since as- Soon'as the seal 47 is broken there is no longer any lifting force on the valve. When the falling yalve contacts the top of the hammer as shown in lFigure l0,y the cycle starts over again, Figure l0 being the same as Figure 5. l l

The above-described mode of operation of the mechanismrequires that the outside diameter of hammer neck and as the valve head enters 36 (i. e. the opemng 1n constriction 8) shall be smaller than the outside diameter of the valve body 44 (iae. the opening in the upper portion of wearl sleeve 49). The difference between these areas should be sufficient so that the upward force developed under pressure will liftthe hammer and valve against their gravitational Weight and against the compression of springs -37 and 56.

Also theclamping force holding the valve and hammery in engagement is dependent on the difference in crosssectional area of the valve body 44 and the outside diameter offhammer head 4G. The countersink 46 in the central passage 45 of the valve should be such `that the clamping force acts onA a restricted annular area 47 to provide a high force per unit area and thus eiect a` good seal. The narrow annular sealing area 47 minimizes the opportunity of chips lodging at this point and the high concentration of clamping force will tend to dislodge or crush any chips which may happen to be there andy whose presence could cause the valve seal1tole`ak.

The mechanism in its preferred form employs the springs 37 and 56 to assist in the downward acceleration of the hammer and valve respectively, but the mechanism may be operated without these springs but at a lower hammer frequency. Also it is not essential that the hammer and the valve be provided with hydraulic cushions as described, but such cushions raise the hammer frequency by shortening the reversing time of these elements.

In order to insure against any possibility of the mechanism jamming in the uppermost position of the hammer, an annular shoulder 58 (Figure 2) is provided on the hammer neck 36. The shoulder 58 acts as a mechanical stop and contacts the bottom of member 8 to arrest the upward motion of the hammer in the' event that the previously-mentioned hydraulic cushion should Vfail to stop the hammer due to wear or other reason. The shoulder 58 is longitudinally so` positioned that it stops upward travel ofthe hammer (in the event of failure of the hydraulic cushion to do so earlier inthe cycle) before the valve reaches its upward limit. `This prevents the mechanism from becoming hydraulically locked. Such a mechanical stop is however not essential to operation of the device.

What I claim as my invention is:

l. In a huid-operated' well-drilling mechanism of the type comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in said housing, an internal constriction in saidhousing belowv said cylinder, means alfording pressurized fluid access to the interior of said housing between said cylinder and said constriction, a bit stem slidably disposed in said housing below said constriction, an elongate hammerin said housing slidably sealed against said constriction and having a 1ongitudinal passage, and a valving element above said hammer having a body portion of larger outside diameter than the inside diameter of said constriction and having a longitudinal passage in register with said hammer passage, the body portion of said valving element being slidablysealed against an internal surface of said cylinder, the improvement which comprises an annular internalV projection inI said cylinder intermediate the closed end andthe .rim ofsaid cylinder,'the body of said valving element being slidably sealed against said projection, an annular head on the lower end of said valving element, and said head forming aA sliding fitin said cylinder below said projection. n

2. In a Huid-operated well-drilling mechanism of the type comprising a tubular housing, an inverted cuplike cylinder longitudinally mounted in said housing, an internal constriction in said housing below said cylinder, means aording pressurized lfluid access to the interior'- of said housing between said cylinder and said 'constriction, a bit stem slidably'disposed in said housing below said constriction, an elongate hammer in said housingslidably sealed against said constriction and havingy a longitudinal passage, and a valving element above said hammer having a body portion of larger outside diameter than the inside diameter of said constriction andhaving a' longitudinal passage in register with said hammer passage, the body portion of said valving element being slidably sealed against an internal surface of said cylinder, the improvement which comprises an annular internal projection in said cylinder intermediate the closed end and the rim of said cylinder, the body of said valving element being slidably sealed against said projection, an annular head on the lower end of said valving element forming a sliding iit in `said cylinder below said projection, a by-pass channel in said valving element adapted to-permit fluid to by-pass lsaid projection when the head of said valving element enters the lower end of said cylinder.

3. In a fluid-operated well-drilling mechanism of the type comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in said housing, an internal constrictionint'said housing below'said cylinder, means alfording pressurized fluid access to the interior of said housing between said cylinder and said constriction, a bit stem slidably disposed insaid housing below said constriction, an elongate hammer in said housing slidably sealed against said constriction and having a longitudinal passage, and a valving element above said hammer having a body portion of larger outside diameter than the inside diameter of said constriction and having an longitudinal passage in register with said hammer passage, the body portion of said valving element being slidably sealed against an internal surface of said cylinder, the improvement which comprises an annular internal projection in said cylinder intermediate the closed end and the rim of said cylinder, the body of said valving element being slidably sealed `against said projection, an annular head on the lower end of said valving element forming a sliding t in said cylinder below said projection, a by-pass channel in said valving element adapted to permit fluid to by-pass said projection when the head of said valving element enters the lower end of said cylinder, and said by-pass channel being cut oft by said projection before the head of said valving element reaches said projection.

4. In a fluid-operated Well-drilling mechanism of the type comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in said housing, an internal constriction in said housing below said cylinder, means affording pressurized uid access to the interior of said housing between said cylinder and said constriction, a bit stem slidably disposed in said housing below said constriction, an elongate hammer in said housing slidably sealed against said constriction and having a longitudinal passage, and a valving element above said hammer having a body portion of'larger outside diameter than the inside diameter of said constriction and having a longitudinal passage in register with said hammer passage, the body portion of said valving element being slidably sealed against an internal surface of said cylinder, the improvement which comprises an annular head on the upper end of said hammer, an annular head on the lower end of said valving element, and the lower end of the longitudinal passage of said valving element having a diameter larger than the outside diameter of the body of said valving element. v k

5. In a fluid-operated Well-drilling mechanism of the type comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in said housing, an internal constriction in said housing Vbelow said cylinder, means affording pressurized fluid access tothe interior of said housing between said cylinder and said constriction, a bit stem slidably disposed in said housing below said constriction, an elongate hammer in said housing slidably sealed against said constriction and having a longitudinal passage, and a valving element above said hammerV having a body portion of larger outside diameter than the vinside diameter of said constriction and having a longitudinal passage in register with said hammer passage, the body portion of said valving element being slidably sealed against an internal surface of said cylinder, the improvement which comprises a neck of reduced diameter intermediate an upper head portion and a lower body portion of said hammer, said neck forming a sliding seal against said constriction, and means sealed to said housing intermediate said bit stem and said constriction forming a sliding seal against the body of said hammer when said hammer is proximate its uppermost position.

6. In a fluid-operated well-drilling mechanism ofthe type comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in said housing, an internal constriction in said housing below said cylinder, means affording pressurized fluid access to the interior of said housing between said cylinder and said constriction, a bit stem slidably disposed in said housing below said constriction, an elongate hammer in said housing slidably sealed against said constriction and having a said bit stem and the bottom of said longitudinal passage, and a valving element above said hammer having a body portion of larger outside diameter than the inside diameter of said constriction and having a longitudinal passage in register with said hammer passage, the body portion Vof said valving element being slidably sealed against an internal surface of said cylinder, the improvement which comprises a neck of reduced diameter intermediate an upper head portion and a lower body portion of said hammer, said neck forming a sliding seal against said constriction, a generally-tubular cage held in said housing coaxially therewith, said cage having a continuous ring fitting tightly in said housing and located between the top of said bit stern and the bottom of said constriction, said cage having below said ring a slotted body portion permitting unobstructed longitudinal motion of said bit stem and said hammer body, and the inside surface of said ring forming a sliding seal against the outside surface of said hammer body when said harnmer is proximate its uppermost position.

7. In a huid-operated well-drilling mechanism of the type comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in said housing, an internal constriction in said housing below said cylinder, means alfording pressurized fluid access to the interior of said housing between said cylinder and said constriction, a bit stem slidably disposed in said housing below said constriction, an elongate hammer in said housing slidably sealed against said constriction and having a longitudinal passage, and a valving element above said hammer having a body portion of larger outside diameter than the inside diameter of said constriction and having a longitudinal passage in register with said hammer passage, the body portion of said valving element being slidably sealed against an internal surface of said cylinder, the improvement which comprises an annular internal projection in said cylinder intermediate the closed end and the rim of said cylinder, the body of said valving element being slidably sealed against said projection, an annular head on the lower end of said valving element, said head forming a sliding fit in said cylinder below said projection, the lower end of the longitudinal passage of said valving element having a diameter larger than the outside diameter of the body of said valving element, a neck of reduced diameter intermediate an upper head portion and a lower body portion of said hammer, said neck forming a sliding seal against said constriction, a generally-tubular cage held in said housing coaxially therewith, said cage having a continuous ring fitting tightly in said housing and located between the top of constriction, said cage having below said ring a slotted body portion permitting unobstructed longitudinal motion of said bit stem and said hammer body, and the inside surface of said ring forming a sliding seal against the outside surface of said hammer body when said hammer is elevated its maximum extent.

References Cited in the tile of this patent UNITED STATES PATENTS 2,661,928 Topanelian, Jr Dec. 8, 1953 

